System and method for communicating messages between a text-based client and a voice-based client

ABSTRACT

A system for communicating messages comprises a session server and a messaging server. The session server receives a call from a first client. The call is intended for a second client. The messaging server is coupled to the session server and receives the call from the session server. The messaging server further communicates a first-text message to an instant messaging client associated with the second client in response to receiving the call. The messaging server further receives a second-text message communicated by the instant messaging client. The second-text message is responsive to the first-text message. The messaging server further converts the second-text message into a voice message and communicates the voice message to the first client.

TECHNICAL FIELD OF THE INVENTION

This invention relates to communication systems and more particularly toa system for communicating messages between a text-based client and avoice-based client.

BACKGROUND OF THE INVENTION

When a person who is talking to someone on a telephone receives a newcall, the person traditionally has two options. First, the person mayput the original call on hold and answer the new call. Second, theperson may allow the caller to be forwarded to voicemail, listen to thevoice message, and then call the party back. The first option ends updisrupting the original call. If the original call is important, thecalled party may not want to disrupt the call. The second option isoften a better choice from the called person's perspective, but it canbe more difficult on the caller. The caller has not been given anyindication of when to expect a return call.

SUMMARY OF THE INVENTION

In accordance with the present invention, the disadvantages and problemsassociated with prior communications systems have been substantiallyreduced or eliminated.

In one embodiment, a system for communicating messages includes asession server and a messaging server. The session server receives acall from a first client. The call is intended for a second client. Themessaging server is coupled to the session server and receives the callfrom the session server. The messaging server further communicates afirst text message to an instant messaging client associated with thesecond client in response to receiving the call. The messaging serverthen receives a second text message communicated by the instantmessaging client. The second text message is responsive to the firsttext message. The messaging server converts the second text message intoa voice message and communicates the voice message to the first client.

Another embodiment of the present invention comprises a method forcommunicating messages. The method includes receiving a call from afirst client. The call is intended for a second client. The methodfurther comprises communicating a first text message to an instantmessaging client associated with the second client in response toreceiving the call. The method continues by receiving a second textmessage generated by the instant messaging client. The second textmessage is responsive to the first text message. The method concludes byconverting the second text message into a voice message andcommunicating the voice message to the first client.

The following technical advantages may be achieved by some, none, or allof the embodiments of the present invention. A first client may place acall intended for a second client that is already conducting anothercall with yet another client. Rather than requiring the first client toleave a voicemail for the second client or requiring the second clientto discontinue the original call or place the original call on holdwhile the second client connects with the first client, the inventionprovides the ability to communicate messages between the first clientand the second client. Using text-to-speech and speech-to-texttechnology along with instant messaging services, the first client mayreceive a suitably formatted response from the second client withoutrequiring an interruption to the original call being conducted by thesecond client. These and other advantages, features, and objects of thepresent invention will be more readily understood in view of thefollowing detailed description and the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention and itsadvantages, reference is now made to the following description, taken inconjunction with the accompanying drawings, in which:

FIG. 1 illustrates one embodiment of a system for communicating messagesbetween a text-based client and a voice-based client;

FIG. 2 illustrates a flowchart that describes the communication ofmessages between clients associated with the system of FIG. 1; and

FIG. 3 illustrates exemplary messages communicated among the componentsof a system of FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 illustrates one embodiment of a system 10 for communicatingmessages between a text-based client and a voice-based client. System 10includes a messaging server 12 coupled to a session server 14 andclients 16. Particular clients 16, such as clients 16 a and 16 b, coupleto session server 14 using data lines 18. Other clients 16, such asclient 16 c, couples to session server 14 using the public switchedtelephone network (PSTN) 20 and a gateway 22. In general, a call 70 isplaced by a first client 16 and intended for a second client 16. If call70 is unable to be completed to the second client 16, such as, forexample, because the second client 16 is connected to another call, thenmessaging server 12 communicates a first text message to an instantmessaging client associated with the second client 16. The first textmessage may indicate that the first client 16 is attempting to connectwith the second client 16. In response, the instant messaging clientassociated with the second client 16 communicates a second text messagethat is responsive to the first text message. Messaging server 12converts the second text message into a voice message for communicationto the first client 16. In this respect, the second client 16 is able tocommunicate with the first client 16, for example, without disruptinganother call being conducted by the second client 16. Furthermore, thefirst client 16 receives a prompt response from second client 16.

Messaging server 12 comprises a processor 30 coupled to a memory 32, afirst interface 34 and a second interface 36. In general, processor 30comprises a central processing unit while memory 32 comprises one ormore components of random access memory (RAM), read only memory (ROM),magnetic computer disk, CD-ROM, other magnetic or optical storage media,or any other volatile or non-volatile storage device that stores atext-to-speech conversion application 40, a speech-to-text conversionapplication 42, an instant messaging application 44, client directory46, configuration data 48, voice files 50, text files 52, and any othersuitable files, applications, instructions, tables, or other informationused to perform the operation of system 10. Although FIG. 1 illustratesmemory 32 as internal to server 12, it should be understood that memory32, or particular items stored therein, may be internal or external tovarious components of system 10, depending on the particularimplementation. Also, memory 32 illustrated in FIG. 1 may be separate orintegral to other memory of system 10. Processor 30 and memory 32execute instructions and manipulate information in accordance with theoperation of system 10.

Interface 34 comprises an Internet Protocol (IP) interface operable tocommunicate with session server 14. In one embodiment, interface 34supports Session Initiation Protocol (SIP) and SIP for Instant Messagingand Presence Leveraging Extensions (SIMPLE). SIMPLE is an extension tothe SIP protocol used by instant messaging clients associated withclients 16. Second interface 36 comprises an audio driver operable tocommunicate with gateway 22 and/or clients 16. In one embodiment,messaging server 12 comprises a unified messaging system that can handlevoice, fax, and regular text messages as objects in a single mailboxthat a user can access either with a regular e-mail client or bytelephone. In general, messaging server 12 supports the followingnetwork, transport, and control protocols: SIP, SIMPLE, InternetProtocol (IP), User Datagram Protocol (UDP), Transport Control Protocol(TCP), Domain Name System (DNS), and Session Description Protocol (SDP).

Session server 14 comprises any suitable server operable to establish aconnection between an originating endpoint of system 10 and a targetendpoint of system 10, such as, for example, connecting a call 70between clients 16 or between a particular client 16 and messagingserver 12. In a particular embodiment, session server 14 comprises aVoice Over Internet Protocol (VoIP) server that performs the functionsof signaling and session management within a packet telephony network.The signaling functionality of session server 14 allows call informationto be carried across network boundaries. The session managementfunctionality of session server 14 provides the ability to control theattributes of an end-to-end call 70. In a particular embodiment, theVoIP protocol supported by session server 14 comprises SIP, which is astandard for multimedia conferencing over internet protocol. In thisembodiment, session server 14 comprises a SIP proxy server that handlesall call processing, SIP requests, and SIP responses. Although thefollowing description of session server 14 is detailed with respect toSIP, it should be understood that server 14 supports other IP telephonyprotocols as well, such as the H.323 protocol.

SIP comprises an application layer control protocol that can be used toestablish, maintain, and terminate calls 70 between two or moreendpoints. Therefore, server 14 can determine the location of a targetendpoint and support address resolution, name mapping, and call routingand redirection. Server 14 can further determine the immediatecapabilities of the target endpoint and determine the highest level ofcommon services between the endpoints. In this regard, conferences areestablished between endpoints using the media capabilities that can besupported by all endpoints. Server 14 can further determine theavailability of the target endpoint. Therefore, if a call 70 cannot becompleted because the target endpoint is unavailable, server 14determines whether the called party is already on the phone or did notanswer in the allotted number of rings. Server 14 then generates amessage indicating why the target endpoint is unavailable. Server 14further establishes a session between the originating endpoint and thetarget endpoint. Therefore, if the call 70 can be completed, server 14establishes a session between the endpoints. Server 14 also supportsmid-call changes, such as the addition of another endpoint to theconference or the changing of a media characteristic or CODEC. Server 14further handles the transfer and termination of calls 70. For example,server 14 supports the transfer of calls 70 from one endpoint toanother. During a call transfer, server 14 establishes a session betweenthe transferee and a new endpoint (specified by the transferring party)and terminates the session between the transferee and the transferringparty. At the end of a call 70, server 14 terminates the sessionsbetween all parties. Session server 14 is associated with memory 50 thatstores addressing information 52 associated with endpoints within system10, and a session table 54 that logs the various sessions hosted bysession server 14.

Clients 16 comprise any suitable devices that may place or receive acall 70. For example, client 16 c may comprise a traditional telephonethat connects to the components of system 10 using PSTN 20. In anotherexample, clients 16 may comprise any suitable combination of aworkstation 60 and an IP phone 62. Workstation 60 may comprise anysuitable processor and memory operable to communicate with sessionserver 14 using data lines 18 and to operate an instant messaging client64. IP phone 62 comprises any suitable IP-based telephone that maycommunicate with components on a local or wide area IP network. In aparticular embodiment, IP phone 62 comprises softphone, such as asoftware based application operated by workstation 60. Such a softphonealso has communication capabilities with an IP network. In general, IPphones 62 can both initiate SIP requests and respond to SIP requests.Instant messaging client 64 comprises a software application thatoperates upon workstation 60 and provides instant messaging services tothe users of workstation 60. Instant messaging client 64 communicatesmessages between workstation 60 and processor 30 of messaging server 12.In addition to text messages, instant messaging client 64 may alsocommunicate audio data, video data, web data, streaming content, files,or any other suitable data between workstation 60 and messaging server12. Various online services, such as America Online, Prodigy, CompuServ,and MSN may provide a suitable instant messaging client 64 for use insystem 10.

Data lines 18 comprise any suitable communication links that supportpacket-based communications. In a particular embodiment, data lines 18support the SIP protocol. PSTN 20 comprises the public switchedtelephone network. Gateway 22 comprises a VoIP communication device thatperfomms a translation function between VoIP conferencing endpoints andother terminals. This function includes translation between transmissionformats and between communications procedures. In addition, gateway 22also translates between audio and video CODECs and performs call setupand clearing on both the packet-switched network side and thecircuit-switched network side. For example, gateway 22 interfacessession server 14 with PSTN 20. Therefore, when a call 70 is placed byclient 16 c using PSTN 20, gateway 22 translates the call formatassociated with PSTN 20 to a call format associated with session server14, such as, for example, SIP or any other suitable VoIP protocol.

In operation, session server 14 receives a call 70 from a first client16 that is intended for a second client 16. For example, call 70 may beplaced by client 16 c using PSTN 20 and received by session server 14using gateway 22. This call 70 may be intended for either of clients 16a or 16 b. In another embodiment, session server 14 may receive a call70 from client 16 a that is intended for client 16 b within system 10.If the call 70 is received through PSTN 20, gateway 22 translates thecall 70 between transmission formats and/or between communicationprocedures from those associated with PSTN 20 to those associated withsession server 14. Upon receiving a call 70, session server 14determines whether the second client 16, the intended recipient of thecall 70, is able to receive the call 70. If session server 14 determinesthat the target endpoint, the second client 16, is available, thensession server 14 establishes a session between the originating endpointand the target endpoint. In this regard, call 70 is completed betweenthe first client 16 and the second client 16.

If call 70 cannot be completed because the target endpoint, secondclient 16, is unavailable or is busy with another call, session server14 forwards call 70 to messaging server 12. In addition, session server14 may communicate call data associated with call 70. The call data mayidentify at least the first client 16 and the second client 16 using atelephone extension, an IP address, a SIP alias, or any other suitableidentifier. Messaging server 12 receives call 70 and the identities offirst client 16 and second client 16 in the call data. Messaging server12 establishes a voice connection 72 with the appropriate first client16 using interface 36. Messaging server 12 then communicates a voicemessage 74 to the first client 16 using voice connection 72. Voicemessage 74 notifies first client 16, for example, that second client 16is unable to take call 70 and requests that first client 16 holds on theline.

Processor 30 operates instant messaging application 44 to generate andcommunicate a text message 76 to instant messaging client 64 associatedwith second client 16. Text message 76 notifies second client 16 thatfirst client 16 is holding on the line, and prompts second client 16 toreply with a message for first client 16. Instant messaging client 64associated with second client 16 communicates a reply text message 78for communication to messaging server 12. The reply text message 78 isresponsive to text message 76 and comprises a suitable message fromsecond client 16 to first client 16. Messaging server 12 receives textmessage 78 and stores text message 78 in a text file 50. Processor 30operates text-to-speech application 40 to convert text message 78 into avoice message 80 to be communicated to first client 16. The voicemessage 80 is stored in a voice file 52, and communicated to secondclient 16 by second interface 36 using voice connection 72. In thisregard, second client 16 is able to communicate with first client 16 ina suitable format, without the need to disrupt a prior call conducted bysecond client 16.

First client 16 is then provided the opportunity to leave a voicemessage 82 for second client 16. Interface 36 captures voice message 82provided by first client 16. First client 16 may then terminate the call70. Processor 30 may provide voice message 82 to second client 16 in anumber of ways. For example, voice message 82 may be provided to a voicemailbox associated with second client 16. Voice message 82 may beprovided as an audio file attachment sent to an electronic mailboxassociated with second client 16. Processor 30 may operatespeech-to-text application 42 to convert voice message 82 into a textmessage 84 for communication to an electronic mailbox associated withsecond client 16. Processor 30 may operate speech-to-text application 42to convert voice message 82 to a text-based instant message 84 forcommunication to instant messaging client 64 associated with secondclient 16.

A particular advantage of system 10 is that a particular second client16 may be conducting a call with another client either within or outsideof system 10 when a call 70 intended for second client 16 is received bysession server 14. Rather than requiring the first client 16 to leave avoicemail for second client 16 or requiring second client 16 toterminate the original call or place the original call on hold whilesecond client 16 connects with first client 16, system 10 provides theability to communicate messages between first client 16 and secondclient 16. Using text-to-speech and speech-to-text technology along withinstant messaging services, the first client 16 may receive a suitablyformatted response from second client 16 without requiring aninterruption to the original call being conducted by second client 16.

FIG. 2 illustrates a flowchart 100 that describes the communication ofmessages between clients 16 of system 10. The method begins at step 102where session server 14 receives a call 70 placed by a first client 16and intended for a second client 16. At step 104, session server 14determines whether call 70 can be completed with second client 16. Ifso, execution proceeds to step 106 where session server 14 connects call70 between first client 16 and second client 16. Execution thenterminates step 128. If call 70 cannot be completed with second client16, as determined at step 104, execution proceeds to step 108 wheresession server 14 forwards call 70 and call data associated with call 70to messaging server 12.

Interface 36 of messaging server 12 establishes a voice connection 72with first client 16, at step 110. Messaging server 12 communicatesvoice message 74 to first client 16 using voice connection 72 at step112. At this point, first client 16 holds on the line and awaits aresponse from second client 16. The remaining steps of flowchart 100allow second client 16 to respond to first client 16 promptly andwithout the need to disrupt any other calls with which second client 16may be participating.

Execution proceeds to step 114 where messaging server 12 communicates atext message 76 to instant messaging client 64 associated with secondclient 16. Instant messaging client 64 associated with second client 16may generate a reply text message 78 that is responsive to text message76. Messaging server 12 receives reply text message 78 at step 116.Reply text message 78 represents a message from second client 16 tofirst client 16. However, because message 78 is text based, first client16 may be unable to receive the message. Therefore, messaging server 12converts reply text message 78 to voice message 80 at step 118. Inparticular, processor 30 may operate text-to-speech application 40 toperform the conversion of reply text message 78 to voice message 80.Interface 36 of messaging server 12 communicates voice message 80 tofirst client 16 at step 120. In this regard, first client 16 promptlyreceives a response from second client 16.

First client 16 is prompted to generate a voice message 82 that isresponsive to voice message 80. If first client 16 generates such areply voice message 82, messaging server 12 receives voice message 82 atstep 122. At this point, call 70 may be terminated by session server 14at step 124. Messaging server 12 may process reply voice message 82 atstep 126 in a number of ways. For example, messaging server 12 maycommunicate voice message 82 to a voice mailbox associated with secondclient 16. In another embodiment, messaging server 12 communicates anaudio file attachment containing voice message 82 to an electronicmailbox associated with second client 16. In yet another embodiment,processor 30 operates speech-to-text application 42 to convert voicemessage 82 to a text message 84 to be communicated to an electronicmailbox associated with second client 16 or to an instant messagingclient 64 associated with second client 16. The method terminates atstep 128.

FIG. 3 illustrates exemplary messages communicated among the componentsof system 10. Path 130 represents a call that takes place between asecond client 16 and a third client 16. In this regard, when firstclient 16 places a call 70 intended for second client 16, second client16 is already conducting another call that is not to be terminated ordisrupted. First client 16 places a call 70 intended for second client16, as represented by path 132. Because second client 16 is alreadyconducting a call with third client 16, as described above withreference to path 130, the call 70 placed by first client 16 isforwarded to the messaging server 12.

Messaging server 12 communicates voice message 74 to first client 16.Messaging server 12 communicates text message 76 to instant messagingclient 64 associated with second client 16. Second client 16communicates reply text message 78 to managing server 12. Messagingserver 12 converts text message 78 into voice message 80 andcommunicates voice message 80 to first client 16. Messaging server 12prompts first client 16 to record a voice message 82. First client 16records voice message 82 and terminates call 70. Messaging server 12processes voice message 82 as described above. In one embodiment,messaging server 12 communicates a text message 84 to instant messagingclient 64 associated with second client 16. Text message 84 may informsecond client 16 that first client 16 left a voice message 82, or it mayactually provide the content of voice message 82 in text format. It isunderstood that the content and/or ordering of one or more messages74-84 may be modified without departing from the scope of the presentinvention.

Although the present invention has been described in detail, it shouldbe understood that various changes, substitutions and alterations can bemade hereto without departing from the scope of the invention as definedby the appended claims.

To aid the Patent Office, and any readers of any patent issued on thisapplication in interpreting the claims appended hereto, applicants wishto note that they do not intend any of the appended claims to invokeparagraph 6 of 35 U.S.C. § 112 as it exists on the date of filing hereofunless “means for” or “step for” are used in the particular claim.

1. A system for communicating messages, comprising: a session serveroperable to: receive a first call from a first client, the first callintended for a second client; determine that the second client isconnected to a second call; and in response to determining that thesecond client is connected to the second call, forward the first call toa messaging server; and the messaging server coupled to the sessionserver and operable to: receive the first call from the session server;and while the second client is connected to the second call:communicate, during the first call, a first text message to an instantmessaging client associated with the second client in response toreceiving the first call; receive a second text message communicated bythe instant messaging client, the second text message responsive to thefirst text message; convert the second text message into a voicemessage; and communicate the voice message to the first client duringthe first call, thereby allowing a user of the second client tocommunicate information to the first client while the second client isconnected to the second call.
 2. The system of claim 1, wherein thesession server forwards call data associated with the first call to themessaging server, the call data identifying at least the first clientand the second client.
 3. The system of claim 2, wherein the messagingserver generates the first text message using at least the call data. 4.The system of claim 1, wherein the instant messaging client operates ona workstation associated with the second client, the workstation havingan internet protocol (IP) address.
 5. The system of claim 4, wherein:the session server establishes a data connection between the messagingserver and the workstation using the IP address of the workstation; andthe first text message is communicated to the instant messaging clientusing the data connection.
 6. The system of claim 5, wherein the secondtext message is communicated to the messaging client using the dataconnection.
 7. The system of claim 1, wherein at least one of the firstclient and the second client comprises an IP phone coupled to thesession server.
 8. The system of claim 1, wherein the first text messageidentifies the first client and indicates that the first client isattempting to connect with second client.
 9. The system of claim 1,wherein the session server comprises a voice-over-internet-protocol(VoIP) proxy server and the first client places the first call using thepublic-switched-telephone (PSTN) network, and further comprising a VoIPgateway that interfaces the VoIP proxy server with the PSTN.
 10. Thesystem of claim 9, wherein the messaging server establishes a voiceconnection with the VoIP gateway and the voice message is communicatedto the first client using the voice connection.
 11. The system of claim1, wherein the voice message comprises a first voice message and themessaging server further receives a second voice message communicated bythe first client.
 12. The system of claim 11, wherein the messagingserver converts the second voice message to a third text message. 13.The system of claim 12, wherein the messaging server communicates thethird text message to at least one of the instant messaging clientassociated with the second client and an electronic mailbox associatedwith the second client.
 14. The system of claim 1, wherein: the sessionserver comprises a voice-over-internet-protocol (VoIP) proxy server; thefirst client places the first call using the public-switched-telephone(PSTN) network; and the first call is associated with a first callformat and further comprising a VoIP gateway that interfaces the VoIPproxy server with the PSTN and associates the call to a second callformat, the second call format comprising a VoIP protocol.
 15. Thesystem of claim 14, wherein the VoIP protocol comprises SessionInitiation Protocol (SIP) and the session server comprises a SIP proxyserver.
 16. A method for communicating messages, comprising: receiving afirst call from a first client, the first call intended for a secondclient; determining that the second client is connected to a secondcall; in response to determining that the second client is connected tothe second call, forwarding the first call to a messaging server forcommunicating a first text message to an instant messaging clientassociated with the second client during the first call; and while thesecond client is connected to the second call, receiving, at themessaging server a second text message generated by the instantmessaging client, the second text message responsive to the first textmessage; converting the second text message into a voice message; andcommunicating the voice message from the messaging server to the firstclient during the first call.
 17. The method of claim 16, wherein theinstant messaging client operates on a workstation associated with thesecond client, the workstation having an internet protocol (IP) address.18. The method of claim 17, further comprising establishing a dataconnection with the workstation using the IP address of the workstation,wherein the first text message is communicated to the instant messagingclient using the data connection.
 19. The method of claim 18, whereinthe second text message is communicated to the messaging client usingthe data connection.
 20. The method of claim 16, wherein at least one ofthe first client and the second client comprises an internet protocol(IP) phone.
 21. The method of claim 16, wherein the first text messageidentifies the first client and indicates that the first client isattempting to connect with the second client.
 22. The method of claim16, further comprising establishing a voice connection with the firstclient, wherein the voice message is communicated using the voiceconnection.
 23. The method of claim 16, wherein the voice messagecomprises a first voice message and further comprising receiving asecond voice message communicated by the first client.
 24. The method ofclaim 23, further comprising converting the second voice message to athird text message.
 25. The method of claim 24, further comprisingcommunicating the third text message to at least one of the instantmessaging client associated with the second client and an electronicmailbox associated with the second client.
 26. The method of claim 16,wherein the first call is associated with a first call format andfurther comprising associating the first call with a second call format,the second call format comprising a voice-over-internet-protocol (VoIP)protocol.
 27. The method of claim 26, wherein the VoIP protocolcomprises Session Initiation Protocol (SIP).
 28. A system forcommunicating messages, comprising: means for receiving a first callfrom a first client, the first call intended for a second client; meansfor determining that the second client is connected to a second call;means for forwarding the first call to a messaging means in response todetermining that the second client is connected to the second call; themessaging means comprising: means for receiving the forwarded firstcall; means for communicating, during the first call, a first textmessage to an instant messaging client associated with the second clientwhile the second client is connected to the second call; means forreceiving a second text message generated by the instant messagingclient while the second client is connected to the second call, thesecond text message responsive to the first text message; means forconverting the second text message into a voice message; and means forcommunicating the voice message to the first client during the firstcall, thereby allowing a user of the second client to communicateinformation to the first client while the second client is connected tothe second call.
 29. The system of claim 28, wherein the instantmessaging client operates on a workstation associated with the secondclient, the workstation having an internet protocol (IP) address. 30.The system of claim 29, further comprising means for establishing a dataconnection with the workstation using the IP address of the workstation,wherein the first text message is communicated to the instant messagingclient using the data connection.
 31. The system of claim 30, whereinthe second text message is communicated to the messaging client usingthe data connection.
 32. The system of claim 28, wherein at least one ofthe first client and the second client comprises an internet protocol(IP) phone.
 33. The system of claim 28, wherein the first text messageidentifies the first client and indicates that the first client isattempting to connect with the second client.
 34. The system of claim28, further comprising means for establishing a voice connection withthe first client, wherein the voice message is communicated using thevoice connection.
 35. The system of claim 28, wherein the voice messagecomprises a first voice message and further comprising means forreceiving a second voice message communicated by the first client. 36.The system of claim 35, further comprising means for converting thesecond voice message to a third text message.
 37. The system of claim36, further comprising means for communicating the third text message toat least one of the instant messaging client associated with the secondclient and an electronic mailbox associated with the second client. 38.The system of claim 28, wherein the first call is associated with afirst call format and further comprising means for associating the firstcall with a second call format, the second call format comprising avoice-over-internet-protocol (VoIP) protocol.
 39. The system of claim38, wherein the VoIP protocol comprises Session Initiation Protocol(SIP).
 40. A system for communicating messages, comprising: a sessionserver operable to: receive a first call from a first client, the firstcall intended for a second client; determine that the second client isconnected to a second call; and in response to determining that thesecond client is connected to the second call, forward the first call toa messaging server; and the messaging server coupled to the sessionserver and operable to: receive the first call from the session server;while the second client is connected to the second call: communicate,during the first call, a first text message to an instant messagingclient associated with the second client in response to receiving thecall; receive a second text message communicated by the instantmessaging client, the second text message responsive to the first textmessage; convert the second text message into a voice message; andcommunicate the voice message to the first client during the first call,thereby allowing a user of the second client to communicate informationto the first client while the second client is connected to the secondcall; wherein the session server comprises a Session Initiation Protocol(SIP) proxy server, the first client places the call using thepublic-switched-telephone (PSTN) network, and further comprising agateway that interfaces the SIP proxy server with the PSTN.